Britain's Lord McAlpine was recently the un-named subject of a BBC documentary alleging child sexual abuse. On Twitter, journalists, celebrities and clued-in everyday citizens subsequently published comments making it easy to figure out who was on the hook. The problem? There was no evidence that McAlpine abused anyone, and everyone--right down to individual tweeters--are now on the hook for libel damages.

1) The legal consensus in the UK is that tweeting is a public act of publishing and that no-one should push gossipy claims of criminality lightly unless they like getting sued.

2) Britain's libel laws are freakily plaintiff-friendly.

Even people who RT'd libelous allusions to McAlpine on Twitter could be sued, the cost of a legal defense is astronomical, and McAlpine's lawyers say they have tallied thousands of individual targets. Their proposed donate to charity-or-be-sued drive is the imbroglio's most surreal moment yet--an ostensibly well-meaning gesture whose power rests on threatening people with expensive lawsuits that they cannot afford to defend, even if no libel was truly committed.

One dark irony of it all is that the BBC was trying to buff its credentials as a hunter of child abusers, having itself been exposed for harboring an egregious one for decades. Notwithstanding Lord McAlpine's innocence, and his right to reasonable justice, here's one explanation for why neither the BBC nor anyone else dared take aim at Jimmy Savile during his lifetime.